Experimental and Quasi-Experimental Designs for Research ~pg.50

(Donald T. Campbell- txtbk)


  1. The One-Shot Case Study: X O
    1. single group studied only once.
    2. total absence of control
    3. no scientific value
    4. minimum reference point
    5. error of misplaced precision?!?!
  2. The One-Group Pretest-Posttest Design: O1 X O2
    1. when nothing better can be done
    2. O1 (Pretest) and O2 (Posttest) difference: rival to the hypothesis that X caused the difference
    3. The first uncontrolled rival hypotheses = HISTORY
    4. In addition to X, lot of things could have happened between O1 and O2
    5. EXPERIMENTAL ISOLATION: think physical science labs.
    6. MATURATION: all biological and psychological processes which systematically vary with the passage of time, independent of specific external events.
    7. SPONTANEOUS REMISSION: wound healing (Can be mistaken for remedial X)
    8. TESTING: effect of pretest itself
    10. INSTRUMENTATION = instrument decay
  3. The Static-Group Comparison: X_ _ O1/O2
    1. Experienced group X is compared with one which has not, for the purpose of establishing the effect of X.



currently recommended

  1. Controls for Internal Validity
  2. Factors Jeopardizing External Validity
  3. Tests of Significance for Design 4


The Solomon Four-Group Design


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